<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <script>
    function show(a, b, ...args, c){
      alert(args);
    }

    show(12, 15, 8, 9, 20, 21, 90);
    </script>
  </head>
  <body>

  </body>
</html>
